This invention relates to a semiconductor device mounted on a board by flip-chip and a method for mounting the same.
Conventionally, a semiconductor device mounted on a board by flip-chip is mounted by inserting solder bumps 13 between pad portions of a semiconductor chip 11 and a board 12 as shown in FIG. 1 and reflowing and melting the solder bumps 13 to electrically connect the pad portions of the semiconductor chip 11 to the board 12.
However, in the above flip-chip type semiconductor device and the mounting method thereof, since the thermal expansion coefficients of the semiconductor chip 11 and the board 12 are different from each other, the solder bump 13 is liable to be destroyed after the surface mounting because of the difference in the thermal expansion between the semiconductor chip 11 and the board 12, thereby causing poor electrical connection. For example, the thermal expansion coefficient of silicon used for the semiconductor chip 11 is approx. 5 .times.10.sup.-6 /.degree.C! and the thermal expansion coefficient of glass epoxy used for the board 12 is 11 to 12 .times.106.sup.-6 /.degree.C!.